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fscache: Provide a function to resize a cookie

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Provide a function to change the size of the storage attached to a cookie,
to match the size of the file being cached when it's changed by truncate or
fallocate:

	void fscache_resize_cookie(struct fscache_cookie *cookie,
				   loff_t new_size);

This acts synchronously and is expected to run under the inode lock of the
caller.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819621839.215744.7895597119803515402.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906922387.143852.16394459879816147793.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967128998.1823006.10740669081985775576.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021527861.640689.3466382085497236267.stgit@warthog.procyon.org.uk/ # v4
This commit is contained in:
David Howells 2021-10-20 14:06:34 +01:00
parent 1f67e6d0b1
commit 16a96bdf92
6 changed files with 82 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
fs/fscache/internal.h
View File

@ -122,6 +122,9 @@ extern atomic_t fscache_n_relinquishes;
extern atomic_t fscache_n_relinquishes_retire;
extern atomic_t fscache_n_relinquishes_dropped;
extern atomic_t fscache_n_resizes;
extern atomic_t fscache_n_resizes_null;
static inline void fscache_stat(atomic_t *stat)
{
atomic_inc(stat);

25
fs/fscache/io.c
View File

@ -291,3 +291,28 @@ void __fscache_write_to_cache(struct fscache_cookie *cookie,
term_func(term_func_priv, ret, false);
}
EXPORT_SYMBOL(__fscache_write_to_cache);
/*
* Change the size of a backing object.
*/
void __fscache_resize_cookie(struct fscache_cookie *cookie, loff_t new_size)
{
struct netfs_cache_resources cres;
trace_fscache_resize(cookie, new_size);
if (fscache_begin_operation(&cres, cookie, FSCACHE_WANT_WRITE,
fscache_access_io_resize) == 0) {
fscache_stat(&fscache_n_resizes);
set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &cookie->flags);
/* We cannot defer a resize as we need to do it inside the
* netfs's inode lock so that we're serialised with respect to
* writes.
*/
cookie->volume->cache->ops->resize_cookie(&cres, new_size);
fscache_end_operation(&cres);
} else {
fscache_stat(&fscache_n_resizes_null);
}
}
EXPORT_SYMBOL(__fscache_resize_cookie);

9
fs/fscache/stats.c
View File

@ -35,6 +35,9 @@ atomic_t fscache_n_relinquishes;
atomic_t fscache_n_relinquishes_retire;
atomic_t fscache_n_relinquishes_dropped;
atomic_t fscache_n_resizes;
atomic_t fscache_n_resizes_null;
atomic_t fscache_n_read;
EXPORT_SYMBOL(fscache_n_read);
atomic_t fscache_n_write;
@ -69,8 +72,10 @@ int fscache_stats_show(struct seq_file *m, void *v)
seq_printf(m, "Invals : n=%u\n",
atomic_read(&fscache_n_invalidates));
seq_printf(m, "Updates: n=%u\n",
atomic_read(&fscache_n_updates));
seq_printf(m, "Updates: n=%u rsz=%u rsn=%u\n",
atomic_read(&fscache_n_updates),
atomic_read(&fscache_n_resizes),
atomic_read(&fscache_n_resizes_null));
seq_printf(m, "Relinqs: n=%u rtr=%u drop=%u\n",
atomic_read(&fscache_n_relinquishes),

4
include/linux/fscache-cache.h
View File

@ -64,6 +64,10 @@ struct fscache_cache_ops {
/* Withdraw an object without any cookie access counts held */
void (*withdraw_cookie)(struct fscache_cookie *cookie);
/* Change the size of a data object */
void (*resize_cookie)(struct netfs_cache_resources *cres,
loff_t new_size);
/* Invalidate an object */
bool (*invalidate_cookie)(struct fscache_cookie *cookie);

18
include/linux/fscache.h
View File

@ -163,6 +163,7 @@ extern struct fscache_cookie *__fscache_acquire_cookie(
extern void __fscache_use_cookie(struct fscache_cookie *, bool);
extern void __fscache_unuse_cookie(struct fscache_cookie *, const void *, const loff_t *);
extern void __fscache_relinquish_cookie(struct fscache_cookie *, bool);
extern void __fscache_resize_cookie(struct fscache_cookie *, loff_t);
extern void __fscache_invalidate(struct fscache_cookie *, const void *, loff_t, unsigned int);
extern int __fscache_begin_read_operation(struct netfs_cache_resources *, struct fscache_cookie *);
@ -366,6 +367,23 @@ void fscache_update_cookie(struct fscache_cookie *cookie, const void *aux_data,
__fscache_update_cookie(cookie, aux_data, object_size);
}
/**
* fscache_resize_cookie - Request that a cache object be resized
* @cookie: The cookie representing the cache object
* @new_size: The new size of the object (may be NULL)
*
* Request that the size of an object be changed.
*
* See Documentation/filesystems/caching/netfs-api.txt for a complete
* description.
*/
static inline
void fscache_resize_cookie(struct fscache_cookie *cookie, loff_t new_size)
{
if (fscache_cookie_enabled(cookie))
__fscache_resize_cookie(cookie, new_size);
}
/**
* fscache_invalidate - Notify cache that an object needs invalidation
* @cookie: The cookie representing the cache object

25
include/trace/events/fscache.h
View File

@ -78,6 +78,7 @@ enum fscache_access_trace {
fscache_access_invalidate_cookie_end,
fscache_access_io_not_live,
fscache_access_io_read,
fscache_access_io_resize,
fscache_access_io_wait,
fscache_access_io_write,
fscache_access_lookup_cookie,
@ -149,6 +150,7 @@ enum fscache_access_trace {
EM(fscache_access_invalidate_cookie_end,"END inval ") \
EM(fscache_access_io_not_live, "END io_notl") \
EM(fscache_access_io_read, "BEGIN io_read") \
EM(fscache_access_io_resize, "BEGIN io_resz") \
EM(fscache_access_io_wait, "WAIT io ") \
EM(fscache_access_io_write, "BEGIN io_writ") \
EM(fscache_access_lookup_cookie, "BEGIN lookup ") \
@ -418,6 +420,29 @@ TRACE_EVENT(fscache_invalidate,
__entry->cookie, __entry->new_size)
);
TRACE_EVENT(fscache_resize,
TP_PROTO(struct fscache_cookie *cookie, loff_t new_size),
TP_ARGS(cookie, new_size),
TP_STRUCT__entry(
__field(unsigned int, cookie )
__field(loff_t, old_size )
__field(loff_t, new_size )
),
TP_fast_assign(
__entry->cookie = cookie->debug_id;
__entry->old_size = cookie->object_size;
__entry->new_size = new_size;
),
TP_printk("c=%08x os=%08llx sz=%08llx",
__entry->cookie,
__entry->old_size,
__entry->new_size)
);
#endif /* _TRACE_FSCACHE_H */
/* This part must be outside protection */